Changes to the water cycle over time; human and physical impacts

Question 1

What is the problem caused by water abstraction and how can aquifers be replenished?

Answer 1

• Water is being abstracted much quicker than it can be replenished.
• Caused by population growth and increased demand for water, the problem will only get worse.
• Aquifers can be replenished by using water from lakes.

Negative feedback as there is less within the stores.

Question 2

What is the problem with farming practices upon the water cycle?

Answer 2

• Irrigation means water is artificially added to fields to improve growing conditions.
• Land drainage involves removing water when the water table is too high to improve soil productivity.

Affects the natural cycle and water table as water is artificially added and removed. All of these processes affect the amount of water in the soil store.

Question 3

How do urbanisation and deforestation affect the water cycle?

Answer 3

• Urbanisation causes a steeper rising limb as the water reaches rivers quickly through purpose-built drains.
  (Positive feedback)
• Deforestation, reduces the amount that’s intercepted so more becomes runoff and on a large scale, it means there is less evapotranspiration which reduces precipitation.
  (Negative feedback)

Question 4

How do storm events change the flows and stores?

Answer 4

More becomes runoff over a shorter period of time as processes such as infiltration are unable to happen quickly enough.
In the wet season, this may lead to severe flooding as the ground is already saturated.